Fixing a cellphone??

I think your luck may be with a can of freeze mist. Just dribble the liquid on to just one part at a time until it boots up. Someone may have more knowledge about what area of the board may be more suspect, therefore the place to start cooling parts in first.

Mikek.

You won't find any bad caps. My guess is you'll find water damage and green slime (corrosion) especially in the battery contact area.

I have the same problem. Everything I learned in kollege is now obsolete and 5 years of junk accumulation has ruined my ability to fix things. By coincidence, I'm now doing a purge and recommend you do the same.

Did the laptop work afterwards?

I usually have either time or money, not both. Motivation tends to be proportional to either the money, or the entertainment value.

No. You lack motivation. Cell phone repair is not easy, especially without schematics and replacement parts. Most everything is on one big board, which means that plugging in modules doesn't really help.

If it ain't broke, you are not trying hard enough.

I beg to differ. MLCC (multi-layer ceramic cap) don't like thermal stressing and will fracture and short. I killed a few larger size MLCC caps that way. You can also do the same type of thermal damage with a soldering iron. Most of the warnings are for soldering, but I believe the problem also exists for freezing.

I see some corrosion and water damage inside cell phones and tablets. I managed to partly destroy my Motorola Droid X2 by using it in the high humidity bathroom while showering.

First one was a learning experience. I tried to go commando and wing it. Had to manage two heat guns and some thermocouples. I'd used paper towel under the foil heat shielding. Trying to put out the fire dislodged some components...game over.

I built a fixture to control air flow and mounted the heat guns so had a free hand and put on several thermocouples. Second two I tried still working fine.

Got two more laptops to be done, but I've already got so many working laptops that I don't need two more...low motivation.

Thanks for the link. At least I'll know how to get it apart.

If it's a mechanical problem, why does it keep working when it gets hot? and continues to work after a long sleep when it's cool. Still thinking it's a brown-out problem with the power supply going out of regulation when the screen first comes on and it's trying to start up everything. I oughta be able to see that on the scope while it's in the boot loop.

I'm also worried about fracturing stuff with cold spray. Thinking about applying the freon to a Q-tip and touching parts with that.

Welcome to Learn by Destroying(tm). You seem to be learning.

Ummm, yeah bad idea. Aluminum foil works well but two heat guns is not a good way with BGA chips. You might try a toaster oven. I've only done two HP laptop motherboards with the toaster oven. Both recovered just fine.

Some LaserJet boards with the traditional crappy BGA soldering. I did

Just flex the laptop motherboard a little. That should give you a failed laptop to practice your reflow soldering.

For cell phones, you should probably buy a cheap USB microscope camera. I have one that I don't recommend, but there are plenty available on eBay and Amazon. You may need to experiment with the power, size, illumination, etc. Be sure to get something with an LED illumination ring around the imager.

I have no idea. Offhand, my guess(tm) would be (in order):

1. Bad soldering, cracked solder connection
2. Broken trace
3. Cracked MLCC capacitor
4. Dirt, crud, corrosion, filth, and metal shavings.

That's possible, especially if the battery is dead or defective.

The freeze spray will drop the temp by about 75C. A soldering iron tip will produce about a 160C temp rise. You're much more likely to kill MLCC caps with an iron than with freeze spray. Still, you should be careful.

Ozone depleting Freon has not been used in freeze spray for maybe 20 years. Tetrafluoroethane is what's used these daze.

I've had this can of freeze spray for 30 years or more. ;-)